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Commit f25cc71e authored by Tim Gardner's avatar Tim Gardner Committed by J. Bruce Fields
Browse files

lockd: nlmclnt_reclaim(): avoid stack overflow 



Even though nlmclnt_reclaim() is only one call into the stack frame,
928 bytes on the stack seems like a lot. Recode to dynamically
allocate the request structure once from within the reclaimer task,
then pass this pointer into nlmclnt_reclaim() for reuse on
subsequent calls.

smatch analysis:

fs/lockd/clntproc.c:620 nlmclnt_reclaim() warn: 'reqst' puts
 928 bytes on stack

Also remove redundant assignment of 0 after memset.

Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: default avatarTim Gardner <tim.gardner@canonical.com>
Reviewed-by: default avatarJeff Layton <jlayton@redhat.com>
Signed-off-by: default avatarJ. Bruce Fields <bfields@redhat.com>
parent deb4534f

fs/lockd/clntlock.c

+11 −1
Original line number Diff line number Diff line
@@ -220,10 +220,19 @@ reclaimer(void *ptr) 
{

	struct nlm_host	  *host = (struct nlm_host *) ptr;

	struct nlm_wait	  *block;

	struct nlm_rqst   *req;

	struct file_lock *fl, *next;

	u32 nsmstate;

	struct net *net = host->net;



	req = kmalloc(sizeof(*req), GFP_KERNEL);

	if (!req) {

		printk(KERN_ERR "lockd: reclaimer unable to alloc memory."

				" Locks for %s won't be reclaimed!\n",

				host->h_name);

		return 0;

	}



	allow_signal(SIGKILL);



	down_write(&host->h_rwsem);
@@ -253,7 +262,7 @@ restart: 
		 */

		if (signalled())

			continue;

		if (nlmclnt_reclaim(host, fl) != 0)

		if (nlmclnt_reclaim(host, fl, req) != 0)

			continue;

		list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted);

		if (host->h_nsmstate != nsmstate) {
@@ -279,5 +288,6 @@ restart: 
	/* Release host handle after use */

	nlmclnt_release_host(host);

	lockd_down(net);

	kfree(req);

	return 0;

}

fs/lockd/clntproc.c

+2 −4
Original line number Diff line number Diff line
@@ -615,17 +615,15 @@ out_unlock: 
 * RECLAIM: Try to reclaim a lock

 */

int

nlmclnt_reclaim(struct nlm_host *host, struct file_lock *fl)

nlmclnt_reclaim(struct nlm_host *host, struct file_lock *fl,

		struct nlm_rqst *req)

{

	struct nlm_rqst reqst, *req;

	int		status;



	req = &reqst;

	memset(req, 0, sizeof(*req));

	locks_init_lock(&req->a_args.lock.fl);

	locks_init_lock(&req->a_res.lock.fl);

	req->a_host  = host;

	req->a_flags = 0;



	/* Set up the argument struct */

	nlmclnt_setlockargs(req, fl);

include/linux/lockd/lockd.h

+2 −1
Original line number Diff line number Diff line
@@ -212,7 +212,8 @@ int nlmclnt_block(struct nlm_wait *block, struct nlm_rqst *req, long timeout) 
__be32		  nlmclnt_grant(const struct sockaddr *addr,

				const struct nlm_lock *lock);

void		  nlmclnt_recovery(struct nlm_host *);

int		  nlmclnt_reclaim(struct nlm_host *, struct file_lock *);

int		  nlmclnt_reclaim(struct nlm_host *, struct file_lock *,

				  struct nlm_rqst *);

void		  nlmclnt_next_cookie(struct nlm_cookie *);



/*